1. Field of the Invention
Aspects of the present invention relate to a method and apparatus for scanning each of a plurality of sheets one by one in order to capture an image of each of the plurality of sheets, without multiple feeding of the sheets and an image forming device and method including the same.
2. Description of the Related Art
When documents are multiply fed in a scanning device (such as a multi-function printer, a scanner, a copy machine, etc.), conventional duplex automatic document feeders (DADFs) do not detect the multiple feeding and scan the multiply fed document. Thus, when a plurality of documents are multiply fed, a user has difficulty in determining if the documents have been multiply fed. Moreover, even when the user determines that the documents have been multiply fed, the user must re-feed the documents and rescan the documents.
A retard roller is used to prevent documents from being multiply fed. Specifically, a feeding roller that feeds sheets stored in a document storage case by using a pick-up roller and rotates in a feeding direction. The retard roller rotates in a reverse direction and is used to separate a plurality of documents. When a sheet of paper is fed, the retard roller does not reversely rotate due to a torque limiter. However, when two or more sheets of paper are fed (i.e., when a document or a paper is multiply fed), since a friction coefficient between the retard roller and the sheets is greater than a friction coefficient between the sheets, the retard roller reversely rotates and separates the sheets.
However, the retard roller, the pick-up roller, and the feeding roller are additionally required to prevent the documents from being multiply fed. Furthermore, a controller to control the coupling pressure between the feeding roller and the retard roller and the torque of the retard roller is additionally required. Moreover, the retard roller does not fully prevent documents or papers from being multiply fed.
Therefore, an apparatus and method to detect multiple feeding of documents and scanning the documents one by one, irrespective of a device such as the retard roller and the torque limiter, are required.